1. Field of the Invention
The present invention relates to a character input device, a character input method and a character input program and, more particularly, to a character input device, a character input method and a character input program which enable accurate input of a large amount of character information by using a photographing device such as a camera.
2. Description of the Related Art
When a document photographed by such an apparatus as a digital camera is taken to a computer as data, because such kind of camera has its limitation of resolution, taking the entire document including the large amount of character information by photographing might result in disabling character recognition. Therefore, when a document including a large amount of character information needs to be taken by photographing with high resolution, it is a conventional methods not to photograph the entire document for once but to macro-photograph the document divided into several regions several times. And those photographed images are taken into a computer and synthesized.
Some conventional character input methods are, for example, disclosed in Japanese Patent Laying-Open (Kokai) No. 2000-278514 and Japanese Patent Laying-Open (Kokai) No. Heisei 10-91722. In these character input methods, characters are recognized from an image photographed not by a camera but a handy scanner or the like and after they are positioned using the recognition results, images are synthesized to obtain the entire image. These methods enable high-quality images scanned by a handy scanner or the like to be effectively input. With an image photographed by a hand-held camera, however, a magnification varies with a distance to a paper or an image slants depending on how a camera is held, so that satisfactory results can not to be obtained in these conventional methods.
At the time of inputting a document into a computer, not an image but character information is most important. Proposed therefore is a technique of synthesizing not images but character recognition results to obtain character information of the entire document. Disclosed, for example, in Japanese Patent Laying-Open (Kokai) No. Heisei 11-196255 and Japanese Patent Laying-Open (Kokai) No. Heisei 11-232378 are techniques of obtaining high-quality camera photographed images by automatically moving a camera or correcting a photographed image, then recognizing characters to determine an overlap between character recognition results and synthesizing character information.
With the above-mentioned method, however, since divisional photographing is performed in a predetermined order to lastly perform character recognition and synthesis. Character recognition result will be confirmed after that. As a result, collating the entire recognition result with the original document takes much labor and time, and for storing photographed images and confirming the same on a screen, a storage capacity for storing all the images is required. In addition, when an error is found, it is necessary to select a character to be corrected and perform correction operations by some means for the purpose of correcting the error, which is a heavy burden on a user.
Downloading characters into a computer is expected to be performed by inputting and using a character string (URL or a mail address) as a part of a document in most of cases. Among means for photographing a character string as a part of a document by a camera and inputting the same is the conventional technique disclosed in Japanese Patent Laying-Open (Kokai) No. 2000-207338. This technique realizes input of a part of character strings on a screen by subjecting only a region set by using a pointing device or the like to character recognition processing on an image photographed by a camera.
This technique fails to take into consideration input of such a long character string that can not be accommodated in one screen. Even if the character string is divisionally photographed a plurality of times and the divisional parts are then connected, it is troublesome to designate a region of the character string to be input at every photographing.
The technique neither takes a case where a character string to be input has a line feed halfway in a document into consideration. Therefore it is necessary, after divisional photographing, to link the images into one character string by using document editor software or the like.
Moreover, when unnecessary characters are printed adjacently before and after a character string to be input in a document, a photographing range should be strictly agreed with the character string to be input to prevent these unnecessary characters from being photographed, which is troublesome work.
The above-described conventional character input methods have the following shortcomings.
First problem is that in order to obtain an image neither with bias nor distortion, photographing manner should be better adapted or images having been photographed should be corrected by image processing by a user.
The reason is that images photographed by a camera, unlike those taken by using a dedicated device for taking in document images such as an optical scanner, have low resolution and distortion and are therefore inappropriate for character recognition. Another reason, as recited with respect to a second problem, is that since it is difficult to rectify erroneous recognition, images more suitable for recognition should be obtained.
Second problem is that confirmation and correction of an erroneous recognition are difficult.
The reason is that since character recognition is performed after divisional photographing of the entire document, confirmation of erroneous recognition takes enormous labor. And even if an error is found, troublesome work of designating the relevant character and selecting or inputting a correct character by some means is required.
Third problem is that in a case where a document is divisionally photographed, when an image which has no overlap portion with images photographed so far is photographed, it is impossible to correctly synthesize the image.
The reason is that when synthesizing results of divisional photographing, information about an overlap portion of each image is used.
Fourth problem is that when performing divisional photographing, holding a camera at the ready to press a shutter button over and over at every photographing is a heavy burden for a user.
The reason is that for divisionally photographing a document of a wide area, it is necessary to hold the camera at the ready each time to trip the shutter as many times as the number of divisions, which work takes much time and labor. In addition, operation of pressing the shutter button causes camera-shake.
Fifth problem is that it is not suitable for inputting a long character string as a part of a document.
The reason is that inputting such a long character string that can not be photographed for once is not taken into consideration. And even when photographing the document divisionally in a few times, a character string to be input in a photographed image should be designated in one manner or another at every photographing, which is troublesome.
Sixth reason is that it is difficult to input a character string having a line feed halfway.
The reason is that inputting a character string having a line feed is not taken into consideration and it is necessary to divisionally input parts of the string and link the same by using character editor software or the like.
Seventh problem is that when unnecessary character strings are printed adjacently before and after a character string to be input, input work is troublesome.
The reason is that a photographing range should be minutely adjusted by moving a camera or a processing range should be strictly designated such that unnecessary characters could not be input.